Friday 5 – 5 Types of Insect Antennae, Part 1

Back in December, I did a Friday 5 that described 5 types of insect legs. In it, I touched on the endless variation insects exhibit and how entomologists have to use a huge number of complicated words to describe all of those parts and their different shapes. Today I thought I’d do the same sort of thing, but with insect antennae. One thing to note though: insect antennae come in many flavors, a lot more than you see in legs. A moth’s antennae are vastly different from the antennae of a termite, which are in turn vastly different from the antennae of the butterflies. So, this will be the first post of a series that will be completed… well, probably when I get enough photos to do all of them! Let’s start with an easy one:

CAPITATE ANTENNAE – KNOBBED ANTENNAE

Capitate antenna

Capitate antennae are antennae that end in an abrupt, rounded knob. As you can see from the drawing, the antenna starts narrow at the base and gets bigger toward the tip, but only right near the tip. You’ll see this type of antennae in the antlions and owlflies, but this is also the standard butterfly style of antenna that you’ve probably seen a million times. You can see the capitate antennae easily in this butterfly photo:

A butterfly's capitate antennae (species unknown)

Clavate antennae – Clubbed antennae

Clavate antenna

Clavate antennae are clubbed antennae, or any antenna that starts off narrow and ends in a broad club. Technically, the capitate antennae of butterflies are also clavate because they are also clubbed, but they’re a special kind of club and get their own name (they’re capitate clavate antennae – whew!). Clavate antennae are very common, especially in the beetles, and there are endless variations on the theme. The antennae of the water scavenger beetle I posted earlier this week exhibits a very fine example of a clavate antenna:

A water scavenger beetle's clavate antenna (Hydrophilus triangularis)

These guys have such beautiful clubs! Complex, almost artfully arranged clubs. Gorgeous!

Geniculate antenna – Elbowed antenna

Geniculate antenna

This is another one you have probably seen before, the geniculate or elbowed antenna. Most ants have these, as do weevils and some bees, and they’re awesome! Clearly, geniculate antennae are antennae that have a distinct bend partway down the length. Check out the sexy bend on this leafcutter ant’s antennae!:

Ant's geniculate antennae (Acromyrmex versicolor)

Setaceous antennae – Hairlike antennae

Setaceous antenna

Setaceous antennae start off strong with a nice, broad segment. Then the rest of the antenna is rather wimpy looking, very thin and narrow. This type of antenna is common in my favorite insects, the dragonflies and damselflies. (Remember the rant I did about damselflies not having long antennae? Setaceous antennae ≠ capitate antennae!). You’ll also see longer setaceous antennae on the cicadas, like this one:

A cicada's setaceous antennae (Cacama valvata)

And last but not least,

Moniliform antennae – Beadlike antennae

Moniliform antenna

I love this type of antenna! They’re so elegant looking. Moniliform antennae are the beadlike antennae, so-called because they look rather like a string of pearls with lovely rounded segments attached to other lovely rounded segments. This form of antenna is found in some beetles and the termites, such as this drywood termite photo from my neck of the woods (taken with my first digital camera, before I knew what I was doing…):

A termite's moniliform antennae (Pterotermes occidentis)

Funny that such elegant antennae are found on a major pest species! This particular termite, however, innocently invades dead branches of the palo verde tree and doesn’t cause any problems at all.

So there you have it! 5 types of insect antennae. Have a marvelous weekend!